During DNA replication, how does the 3'→5' exonuclease activity of DNA polymerase contribute to replication fidelity?
Answer
It removes incorrectly paired nucleotides, allowing correct base incorporation.
The correct answer is It removes incorrectly paired nucleotides, allowing correct base incorporation. — Replication proceeds with higher fidelity.
Step-by-step solution
- DNA polymerase adds nucleotides from 5' to 3' direction.
- If a mismatched base is incorporated, the polymerase detects the error.
- The 3'→5' exonuclease domain cleaves the terminal mismatched nucleotide.
- The correct nucleotide is incorporated after the mispair is removed.
- Replication proceeds with higher fidelity.
Common mistake: Confusing the exonuclease activity with the polymerase activity, ignoring its role in error correction.
Concept tested: DNA replication proofreading
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